Mapping current and potential honey production from the Leptospermum genus in Australia

Simon Williams

doi:10.25907/00207

Australia has undeveloped potential to produce medicinal Leptospermum honey from its 84 endemic Leptospermum species. A limitation on production is the general lack of knowledge, among the beekeeper community on species identification and activity. This fundamental knowledge gap is holding back the Australia honey industry from reaching its full Leptospermum honey potential. As part of the AgriFutures (previously RIRDC) Honey Bee programs project "Active Australian Leptospermum honey: new sources and their bioactivity" (PRJ-009186) an Australian wide survey was undertaken of the nectar composition of the Leptospermum genus and its derived honey. The sole New Zealand member of the Leptospermum genus, L. scoparium was the first found to produce honey with increased antimicrobial activity measured as non-peroxide activity (NPA). The honey has found applications in topical wound treatments increasing its value and beekeeper's income. The compound methylglyoxal (MGO) found in Leptospermum honey correlates with the NPA and is derived from the dihydroxyacetone (DHA) found in Leptospermum nectar. Previous studies have confirmed the presence of MGO and DHA in Australian Leptospermum nectar and honey, but knowledge of the DHA potential of individual species is limited. Identifying the DHA potential of Leptospermum species, will provide information allowing Australian beekeepers to grow the production of bioactive Leptospermum honey through targeting high DHA species and in turn increase their financial returns. Leptospermum nectar and derived honey was collected from across Australia with the assistance of collaborators. Samples were analysed by RP-HPLC-DAD. Nectar samples were tested for DHA and total sugar (Tsugar) content, while honey samples were assayed for MGO, DHA and 5-hydroxymethylfurfural (HMF). Collaborators at the University of Technology Sydney performed well-diffusion bioassays for Total Activity (TA) and NPA. Individual results were provided back to beekeepers to assist in apiary site decisions, plantation developments and Leptospermum tree breeding. The assistance of industry collaborators allowed a large dataset (Honey, n = 5906, Nectar n = 3179) to be collected from across Australia. The results identified new Leptospermum honey production regions capable of producing honey with high levels of antimicrobial properties within Australia, increasing the available sites that beekeepers have access to for Leptospermum honey production. The nectar DHA potential of 55 out of 84 endemic species was determined. DHA levels ranged from non-detectable in L. laevigatum and L. trinervium to 16,000+ mg/kg in L. whitei and L. speciosum illustrating that DHA potential is not consistent across the genus. Therefore, DHA content is not a characteristic of the entire Leptospermum genus and care is required to target the correct species for antimicrobial Leptospermum honey production. To assist in targeting the correct species an identification guide was created for beekeepers, using morphological and photographic data collected during the survey. Comparing the Leptospermum honey and nectar data has concluded that there is still untapped potential within Australia to increase the quantity and quality of the produced Leptospermum honey. Harnessing the excess potential will increase the value of the Australian beekeeping industry and Australia's reputation for honey production.

Mapping current and potential honey production from the Leptospermum genus in Australia

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